If you need to give a presentation or demonstration using your iPad-2 you can either cable it to a projector/display or you might consider using an Apple TV.  The Apple TV supports the AirPlay interface and the iPad-2 supports mirroring of its display to the AirPlay interface.  Apple TV costs $100 and has an HDMI output that you can cable to a projector or display.    It does mean that you have to have a wifi network available so that the iPad can stream to the Apple TV.  This is a relatively cheap and quick to setup means of getting your presentation onto a monitor without using a cable.  This allows you to be mobile while giving your presentation which is another benefit.  For demonstrations mirroring allows your audience to see exactly what your apps are doing.